Are you ready for tax day?

Tax filing day is just around the corner, but some Americans may not be ready to submit their returns by April 15. Others may not have the cash to pay the tax they owe.

Ignoring the deadline can cost workers plenty in penalties and interest. And this year, it also could delay their rebates, because the government's promised stimulus program checks are being calculated off federal tax returns.

"People know April 15 is the deadline," said Greg Rosica, co-author of The Ernst & Young Tax Guide 2008. "But sometimes they don't have their information together, or they might be missing some information or they just haven't had time."

Taxpayers who think they're going to miss the deadline should ask the Internal Revenue Service for more time to file. That requires them to submit Form 4868, Application for Automatic Extension of Time to File U.S. Individual Income Tax Return, Rosica said.

Extensions are granted automatically and will give taxpayers until Oct. 15 to file taxes.

Last year, some 10 million taxpayers filed for extensions. This year, the IRS projects the number at 10.3 million.

Those who file by the Oct. 15 extension deadline still will qualify for the federal rebates, which will provide some 130 million Americans with checks of $600 for an individual, $1,200 for a couple and $300 for each dependent child. The program was set up to provide funds to consumers as a way to stimulate the flagging U.S. economy.

Taxpayers need to remember, though, that filing for an extension doesn't get them off the hook if they owe taxes.

"In applying for the extension, you still need to come up with some estimate of whether you owe additional money to the IRS," and pay that amount by April 15, Rosica said.

People who are short of cash have some options if they can't pay what they owe, said Mark Luscombe, principal tax analyst at CCH Inc. of Riverwoods, Ill. The company is a division of Wolters Kluwer, which provides tax information and services to tax professionals.

"If it's a short-term cash flow problem, you might consider paying by credit card with the hope you can pay off the credit card in fairly short order," Luscombe said. "Or maybe you can borrow from a bank or from your family."

Another alternative, Luscombe said, is for taxpayers who can't pay immediately to check whether they qualify for an installment agreement with the IRS.

The IRS offers two types of payment agreements. A short-term extension generally requires full payment within 120 days. A monthly plan, or installment agreement, can be set up online for taxpayers who owe less than $25,000 and are able to pay the balance within 60 months. Fees and interest are charged.

Taxpayers can determine if they're eligible by going to the IRS Web site at www.irs.gov and clicking on the Online Payment Agreement link or by calling 800-829-1040.

There's a steeper penalty for failure to file than there is for failure to pay, but both can be costly for the taxpayer.

The penalty for not filing is 5 percent of the unpaid taxes for each month that a return is late, up to 25 percent.

The failure-to-pay penalty is 0.5 percent of unpaid taxes per month. It doesn't apply during the automatic six-month extension period if the taxpayer has paid at least 90 percent of his or her tax liability by April 15. Interest is charged, too, currently at a rate of 6 percent, according to the IRS.

Some Americans get automatic extensions to file:

- U.S. citizens living outside the United States and Puerto Rico have an extra two months to file their federal returns. combat zone localities generally can delay filing until 180 days after the soldier leaves the combat zone.

- In some designated disaster areas, where residents have been harmed by hurricanes or tornadoes, there can be announced extensions. This year, residents in parts of Illinois, Georgia, Missouri and Arkansas affected by floods and storms have filing and payment deadlines in May.

For the record, the IRS also charges a fee if a taxpayer's check bounces - 2 percent of the face value of the check or $25, whichever is less.